The present invention relates to ozone generators adapted for ozone generation by subjecting oxygen to a high-frequency alternating current (AC) of high voltage over a dielectric medium. More precisely, the invention relates to an ozone generator system wherein a multitude of plate type ozone generators are arranged in a block and wherein one or several blocks may be comprised in a modular ozone generator system.
Ozone has highly oxidising properties and is used, preferably in diluted form, for sterilisation of water. For example, sewage water can be treated with the aim of decomposing or eliminating environmentally or health hazardous substances therefrom, as well as removing unpleasant odours from the water, and drinking water can be pre-treated with the intention of improving the quality of the water. Other areas of use are e.g. as a bleaching agent in the paper industry, for air cleaning and for performing certain oxidation reactions within organic chemistry.
Ozone is produced by letting oxygen, or a gas rich in oxygen, pass through an electrical discharge. Oxygen or an oxygen-rich gas is thereby allowed to flow through a chamber in an ozone generator, said chamber being defined either by two co-axial tubes, or a series of plates, between which tubes or plates an electrical discharge is taking place. In this description, the terms space and chamber are used as denomination for the same thing, i e. the location inside the ozone generator where existing oxygen or oxygen-rich gas is converted into ozone. The first mentioned type of ozone generator is, for industrial purposes, very large and bulky, and difficult and costly to manufacture and maintain. The second type of ozone generator, here called the plate type, is less demanding in terms of economy and space. As the demand for reliable, large capacity ozone generators tends to increase, plate type ozone generators are often arranged on top of each other in blocks, whereby larger ozone generator systems can be obtained. Some examples of such ozone generator systems are disclosed in WO 97/01507 by Arlemark, and in U.S. Pat. No. 5,435,978 by Yokomi.
One problem associated with ozone generators is connected with the chamber, in which oxygen in the form of oxygen gas or a gas rich in oxygen is converted into ozone, having at least one delimiting surface made of a dielectric material, a so called dielectric. This dielectric is used for the purpose of generating a corona during the discharge between a high-voltage electrode and ground, and normally consists of a ceramic or glass material. Pressure variations in the gas fed into the chamber, for example caused by pressure shocks in the system when the gas supply is switched on or off, will generate high strains in the ceramic material, entailing a risk of cracking it. This problem naturally also tends to increase if, with the aim of increasing the capacity, an increased pressure of the introduced oxygen gas is used. If, furthermore, there is an imbalance in pressure and/or flow between different generators, and between the inlet and outlet ports of the individual generators, the stress upon the total system will be even higher. In ozone generator systems arranged in blocks, it is a further problem if the entire system has to be closed down if one generator breaks down.
Another problem is associated with the very reactive properties of the ozone entailing a tendency for hoses and rubber seals to deteriorate and cause leakage. This applies for example to the seals and gas lines required in connection with the oxygen inlets and the ozone outlets. In ozone generator systems having several generators in a block, this problem will become especially obvious, as at least one inlet and one outlet is required for each generator.
Another problem connected to large ozone generator systems is that they have to be arranged at the location where the ozone is to be used, due to the short life span of the ozone before it disintegrates. As a consequence of the ancillary equipment, such as the connections required for oxygen, ozone and cooling water, having to be constructed on site, the cost of installation tends to become very high.
A general object of the present invention is to provide an ozone generator that eliminates the problems of the known art.
An aspect of this object, using an arrangement of an ozone generator system in which generators are arranged in blocks, is to increase the productivity and improve the efficiency compared to known ozone generator systems, and, beyond that, prevent parts of the device from being damaged or to degenerate due to vibrations and shocks encountered during operation, caused by pressure shocks and excessive pressure in the introduced gas, the electrical discharges in the generator chambers, or uneven gas or coolant flows.
Another aspect of this object is to provide a design of a block type ozone generator system adapted for easy maintenance, and arranged so as to be minimally sensitive to the reactive effect of the ozone.
A further aspect of this object is to provide an ozone generator system designed in such a way that existing moisture in the introduced gas is expelled from the system during operation.
Still another aspect of this object is to provide a design allowing easy de-aeration of the system coolant.
Still another aspect of this object is to provide a design eliminating differences in pressure and flow within the ozone generator system.
Still another aspect of this object is to provide a design allowing easy checking of seals in the gas system.
Consequently, the present invention relates to an ozone generator system in which a multitude of plate type ozone generators is arranged adjacent to each other in a block. Each ozone generator comprises a high-voltage electrode, a ground electrode and a dielectric, and a chamber, located between said electrodes, for converting oxygen to ozone by a corona discharge between said electrodes over said dielectric. Further, each chamber is provided with an inlet for oxygen or an oxygen rich gas and an outlet for ozone. Said ozone generators are arranged in a block rack adapted for fixing the ozone generators into said block, said block and block rack defining a block module. The invention is characterised by said block rack comprising an inlet port adapted for the introduction of oxygen and an outlet port adapted for the discharging of ozone created through conversion in the generators comprised in the block module. A multitude of first conduits, each running between said inlet port and one chamber inlet, and a multitude of second conduits, each running between said outlet port and one chamber outlet, are provided within said block rack.
By providing conduits within the block rack, running to and from all generator chambers in the block module, no hoses will be needed, and the number of seals required will be reduced, as conduit junctions can be arranged entirely without joints. Through providing said conduits in such a manner that the distance between the block rack inlet and outlet will have the same length, regardless of which generator the introduced gas passes through inside the module, an even gas flow and an even gas pressure is achieved through parallel connection, securing an increased reliability of operation and allowing operation with an increased gas pressure.